Over a substantial period of time, food molding machines that utilize reciprocating mold plates have proved quite versatile and economical in operation. Machines of this sort that have been successful commercially are described in detail in a series of United States patents, particularly Reissue Nos. Re. 30,096, 4,054,967, 4,182,003, and 4,768,260. By changing the tooling in the mold stations in these machines, all are readily adapted to the production of ground meat patties in a wide variety of varying dimensions and weights. With other tooling in the same mold stations, these machines can economically and effectively produce food products from chopped meat, from shredded meat, from fish, and from a variety of other food materials. Indeed, in the production of some poultry products the meat is not even cut up to any appreciable extent before being fed into the machines; the pressures that these machines develop are sufficient to permit the machines to work with whole chunks of some meats, poultry, fish, and other food materials.
On occasion, reciprocal mold plate food patty molding machines have been adapted to the production of elongated rod-shaped food products such as sausages. Generally speaking, however, these endeavors have not been particularly successful. The mold plate for a machine of this kind can be formed with a series of narrow, elongated cavities simulating the desired rod-like shape, but cavities of this sort present appreciable difficulties with respect to ejection of the molded food products by conventional knockout mechanisms. The food products themselves are not of circular cross-sectional configuration and cannot have that configuration when the machines and mold plates are used in the customary manner. Generally speaking, attempted use of a machine of this kind for the manufacture of a truly rod-shaped molded food product has not been effective from an economic standpoint and has not proved commercially desirable.
In some attempts at conversion of a reciprocating mold plate food product molding machine to the manufacture of rod-shaped food products, the mold plate itself has been replaced by a series of tubes, or by a housing with a plurality of elongated holes, that function as mold cavities. Rods move into and out of these mold tubes, two rods for each tube, in the course of the molding operations. In such machines, the pair of mold rods for each tube/hole usually start the mold filling part of the cycle either in contact or closely adjacent to each other; as the food product is pumped into the mold tube, the rods separate from each other. Ultimately, the rods must be stopped at a spacing determined as the ultimate length of the molded food product. This concept, which has been tried in various forms, introduces undue complexities into the operation of the machine because it is essential to move one or both mold rods of each pair during each mold filling operation, either with a separate drive or in response to the pressure filling of the mold tube. Food product length, diameter, and weight adjustment can be difficult and complex in a machine of this kind, and maintenance problems may be exacerbated. These same machines may also have product quality difficulties due to entrapped air in the mold tubes. Thus, a conversion of this sort, adapting a reciprocating mold plate machine to the production of rod-shaped food products such as sausages, presents appreciable problems.